Article date: December 1973
By: D. M. PATON in Volume 49, Issue 4, pages 614-627
The mechanism of efflux of (—)‐[3H]‐noradrenaline was examined in rabbit atria, which were pretreated with reserpine and pargyline.
Between 40 and 100 min, efflux occurred predominantly from a single intraneuronal compartment.
Efflux was rapidy increased by (—)‐ and (+)‐noradrenaline, tyramine and (±)‐metaraminol, but not by (±)‐isopropylnoradrenaline or (±)‐normetanephrine. The increase in efflux produced by (—)‐noradrenaline was inhibited by cocaine and desipramine but not by lidocaine.
Spontaneous effluxes, and those accelerated by (—)‐noradrenaline, were temperature‐sensitive.
Efflux was increased by ouabain, omission of K+, metabolic inhibition and lowering of the external Na+ concentration. These effects were significantly reduced by cocaine and desipramine but not by lidocaine.
These findings provide evidence that the efflux of [3H]‐noradrenaline from adrenergic nerves occurs by a cocaine‐sensitive, carrier‐mediated process. The characteristics of the efflux process are compatible with, but not conclusive proof for, the Na+‐gradient hypothesis.
The mechanism of efflux of (—)‐[3H]‐noradrenaline was examined in rabbit atria, which were pretreated with reserpine and pargyline.
Between 40 and 100 min, efflux occurred predominantly from a single intraneuronal compartment.
Efflux was rapidy increased by (—)‐ and (+)‐noradrenaline, tyramine and (±)‐metaraminol, but not by (±)‐isopropylnoradrenaline or (±)‐normetanephrine. The increase in efflux produced by (—)‐noradrenaline was inhibited by cocaine and desipramine but not by lidocaine.
Spontaneous effluxes, and those accelerated by (—)‐noradrenaline, were temperature‐sensitive.
Efflux was increased by ouabain, omission of K+, metabolic inhibition and lowering of the external Na+ concentration. These effects were significantly reduced by cocaine and desipramine but not by lidocaine.
These findings provide evidence that the efflux of [3H]‐noradrenaline from adrenergic nerves occurs by a cocaine‐sensitive, carrier‐mediated process. The characteristics of the efflux process are compatible with, but not conclusive proof for, the Na+‐gradient hypothesis.
DOI: 10.1111/j.1476-5381.1973.tb08537.x
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